Boola is a name that appears on the map with nothing around it, and that is a fair description of this stretch of the Alborz. There are few villages, little traffic and almost no services, and the sense of space is considerable.
The label also names Bagh-e Abbasabad, the Abbasabad Garden, which belongs to a different world. It lies on the Mazandaran side, in the lowlands near Behshahr, and was laid out for Shah Abbas I, the Safavid ruler who loved this green Caspian region and built roads, bridges and a palace here in the early seventeenth century. It is one of the Persian Gardens that UNESCO listed in 2011, a design in which water, shade and geometry create an earthly paradise, and the word paradise comes from an old Persian term for an enclosed garden.
The contrast between the two sides of the Alborz is the great theme of any journey here. On the southern side the slopes are dry, rocky and covered with thorny scrub, while on the northern side, just a few kilometres away, thick forest drips with moisture and the air smells of damp leaves. The mountains hold back the clouds, so the north gets the rain and the south gets the sun. Passes cross the crest by tunnels and switchbacks, and the weather on top can change in minutes, with mist, snow and fierce wind.
Roads here are demanding. They are steep, narrow and often in poor repair, with trucks grinding up the grades and long stretches without a village. Winter snow can close the passes, and spring brings rock falls and mud. Late spring and early autumn are the best times, when the days are clear and the roads are clear.
Services are scarce. No sizeable town lies close, so fill the tank and carry water, food and warm clothing. Check local advice on conditions and access before you set off.